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ISO1541: Can GND1 and GND2 differ by -7V?

Dave D'Epagnier
Prodigy 180 points
Part Number: ISO1541

Can VCC1 be +3.3V and GND1 be 0V, along with VCC2 being -2V and GND2 be -7V?

I want to do this so I can interface a microcontroller running at VCC = 3v, GND =0v to the VCC1 side, to an LTC2945 power monitor measuring a negative supply of -7V and putting out -2V on its INTVCC pin to the VCC2 side.

In short, can GND1 and GND2 differ by 7V with one of them being at 0V and the other at -7V?

  • 0
    TI__Mastermind 23685 points

    Hello Dave,

    Two sides of a digital isolator can be powered at different voltages. (+) [FAQ] Can I power the two sides of a digital isolator with different voltages?. Similarly, due to the isolation the side 1 and side 2 grounds can be at different potentials with no issue.

    Based on your description, I am assuming the -7V is the local ground for the secondary side and the absolute maximum ratings are still observed (meaning locally, VCC is 5V and GND2 is 0V). Side 1 and side 2 grounds are rated for a potential difference of ~400Vrms (this is Maximum repetitive peak isolation voltage; Viorm/1.414).

    Best,
    Andrew